CHAPTER 4 REPETITIVE EXECUTION

Counter-Controlled DO Loops

DO Number = 1, 9 PRINT *, Number, Number**2 END DO

DO Number = 9, 1, -1PRINT *, Number, Number**2

END DO

Example: Summation

INTEGER :: Number, I, SumREAD *, NumberDO I = 1, Number

Sum = Sum + IEND DO

Example: A Multiplication Table

DO M = 1, Last_MDO N = 1, Last_N

Product = M * NPRINT *, M, “ “, N, “ “, Produ

ctEND DO

END DO

DEPRECIATION (折舊 ) TABLES Depreciation is the decrease in value over time of so

me asset due to wear and tear, declining price, and so on. For example, suppose that a company purchases a new robot for $20,000 that will be used on its assembly line for 5 years. After that time, called the useful life of the robot, it can be sold at an estimated price of $5,000, which is the robot’s salvage value. Thus, the value of the robot will have depreciated $15,000 over the 5-year period. A program is needed to calculate depreciation tables that display the depreciation in each year of the item’s useful life.

A Robotic Arm

DEPRECIATION TABLES

Method = 1 (The straight-line method)Depreciation = Amount / UsefulLife

Method = 2 (The sum-of-the-years’-digits method)Sum = 1 + 2 + … + UsefulLifeDepreciation = (UsefulLife – Year + 1) * Amount / Sum

General DO Loops: DO-EXIT Construct

DOIF (Sum > Limit) EXITNumber = Number + 1Sum = Sum + Number

END DO

Pretest Loop: “test-at-the-top” loop

DOIF (logical-expression) EXITstatement-sequence

END DO

Posttest Loop: “test-at-the-bottom” loop

DOstatement-sequenceIF (logical-expression) EXIT

END DO

DO Loop: Other Type

“Test-in-the-middle” loopQuery-controlled input loops

Query (疑問 ); Control (控制 )

CYCLE Statement

DO (p. 214, Textbook)

READ *, Celsius IF (Celsius < 0.0) PRINT *, “** Temperature must be 0 or above **” CYCLE

END IF (p. 214, Textbook) READ * Response IF (Response == “N”) EXITEND DO

Named DO Constructs

Outer: DO M = 1, Last_MInner: DO N = 1, Last_N

Product = M * NPRINT *, M, “ “, N, “ “, Pro

ductEND DO Inner

END DO Outer

Mean Time to Failure (故障平均時間 )

One important statistic (統計 ) used in measuring the reliability (可靠度 ) of a component in a circuit is the mean time to failure, which can be used to predict the circuit’s life time. This is especially important in situation in which repair is difficult or even impossible, such as a computer circuit in a space satellite.

Mean Time to Failure

Suppose that NASA (National Aeronautics and Space Administration) has awarded an engineering laboratory a contract (合約 ) to evaluate the reliability of particular component for a future space probe (探測 ) to Mars (火星 ). As part of this evaluation, an engineer at this laboratory has test of these circuits and recorded the time at which each failed; now she would like a program to process this data and determine the mean time to failure.

Space Probe (太空探測 )